Taxonomy

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Domain: Bacteria / Phylum: Spirochaetes

Found in contaminated H2O, soil, sewage, and bodies of humans/animals. All species stain as gram negative cells. All are motile by axial filaments. They can be aerobic, anaerobic, or facultative anaerobic.

Phylum: Spirochaetes Species: Treponema pallidum

Causative agent of syphilis. Transmitted by sexual contact of all kinds. Incubation is 3 weeks to several months. Testing is done using a slide antibody test. Progresses slowly in three stages. Treatment: Penicillin, IV, IM

Causes leptospirosis. Causes a zoonotic infection in humans. Acquired through contact with contaminated urine in water, soil, or directly from dogs, cats. Infection occurs by direct contact. Most cases: fever, recovering in 2-3 weeks. 5-30% of untreated cases result in death. Sometimes severe liver or kidney disease. Renal failure is most common cause of death. Treatment: doxycycline, penicillin

Phylum: Proteobacteria Genus: Brucella

Causes brucellosis in cattle, goats, and hogs which can lead to spontaneous abortion. Spread by direct contact with infected tissues and contaminated feed. Can infect humans (brucellosis). Results from ingestion of contaminated, unpasteurized dairy products OR contact with infected animal carcasses. Most infections occur in slaughter houses. Undulant fever: 100-200 cases per year. Treatment: doxycycline and gentamycin for 6 weeks.

Phylum: Proteobacteria Genus: Rickettsias

Rod shaped or coccobacilli. Gram negative. Non-motile. Transmitted by fleas and ticks to humans. Similar to viruses. Obligate intracellular parasites.

Phylum: Proteobacteria Species: Rickettsia prowazekii

Causes epidemic typhus. Transmitted by lice, excreted through the GI tract of the louse. Feces are rubbed into wound when bitten host scratches the bite. Typically found in unsanitary conditions. High, prolonged fever for two or more weeks. Red spots. Myocardial and central nervous system functioning are affected. If untreated, mortality rate up to 60%. Treatment: tetracycline, chloramphenicol.

Non-endospore forming diplococci, unencapsulated. May be aerobic or facultatively anaerobic. Contain capsule, pili. Most species are normal inhabitants of upper respiratory and alimentary tract.

Phylum: Proteobacteria Species: Neisseria gonorrhoeae

Causes gonorrhea. Untreated infections can result in complications involving joints, heart, eyes, pharynx, or other body parts. Infection spreads along fallopian tube. Men: Single exposure results in a 20%-30% chance of infection. Primary site is urethra. Women: Single exposure results in a 60%-90% chance of infection. Primary site is the endocervix. Treatment: ciprofloxacin, penicillin

Causes whooping cough. Spread by airbone droplets. The only host is humans. It is tropic for ciliated bronchial epithelium. Non-motile rod, virulent forms are encapsulated. Whooping cough: 50 coughing attacks per day for 2-4 weeks. 2014: 18,000 cases due to lack of vaccination. Vaccine: DaTP. Treatment: erythromycin, not effective in paroxysmal phase.

Phylum: Proteobacteria Genus: Enterobacteria

Primary inhabitants of the lower GI tract of humans/animals. In humans they are the main facultative content of the colon. Also found in the female genital tract and transients on the skin. Most common colonizers of humans are: E. Coli, Klebsiella, Proteus, and Enterobacter. All species produce Lipopolysaccharide LPS (a powerful endotoxin). Facultatively anaerobic.

Phylum: Proteobacteria Subspecies: Escherichia spp.

Are facultative anaerobes. Most common inhabitant of the GI tract. Normal flora. All species ferment glucose to gas and acid.

Phylum: Proteobacteria Species: E. coli

Most common cause of urinary tract, bladder, and renal pelvis and kidney infections. Causes 35% of all UTIs. Cystitis. Causes 75% of all Pyelonephritis.

Phylum: Proteobacteria Species: E. coli O157:H7

Causes hemolytic uremic syndrome due to shiga toxin & LPS entering the blood stream. Transmitted to humans from cattle by undercooked beef and contaminated raw milk. Also known as EHEC. First outbreak in 1982. 0.9/100,000 in US.

Causes typhoid fever, an important cause of mortality and morbidity worldwide. Spread only in feces of humans. Incubation period is 13 days. Prolonged fever, multi-organ system involvement. Treatment: electrolytes, antibiotics.

Causes a less severe form of shigellosis. Most comon species in the US.

Phylum: Proteobacteria Species: Klebsiella pneumoniae

Causes classic lobar pneumoniae in aged persons and or immunocompromised individuals. Most common cause of acute bacterial respiratory pneumonia in male alcoholics over 40 years old. Commonly found in normal intestinal flora.

Most common cause of meningitis in young children. Carrier rates are as high as 80% in children, 20-50% in healthy adults. Transmission is by respiratory droplets. Major infections in children are: sinusitis, otitis, meningitis, epiglotitis, also arthritis. Treatment: ceftriaxone, trimethoprim-sulfameethoxazole. Untreated meningitis = 90% mortality. Hib vaccine.

Causes pneumonia called Legionellosis. Contaminants of warm water supplies in hospitals, water in cooling towers of air conditioners. Gram negative. 6 species have been discovered. 25,000 cases each year.

Causes tularemia (rabbit fever). Symptoms are similar to the plague. Contact to humans is by direct contact of infected animal (feces or urine) or by vector. Causes swelling in the lymph nodes. In the US - 200 cases in hunters in 2010. Without treatment: death occurs in 5-30% of cases

Phylum: Proteobacteria Species: Vibrio cholerae

Causes cholera, a severe gastroenteritis. Requires ingestion of large numbers of bacteria to overcome the acidic environment of the stomach. Commonly found in H2O. Treatment: electrolyte, fluid replacement, tetracycline can shorten symptoms.

Phylum: Proteobacteria Species: Campylobacter jejuni

Found in poultry and cattle. Causes an infections diarrhea. A new contributor to outbreaks of food born disease in fast food restaurants. Leading cause of foodborne illness in the US with 2 million cases/year.